Walter Reed National Military Medical Center Bethesda, MD, United States
Kathryn E. Driggers, MD, Amy L. Austin, MD, Jared S. Magee, DO, MPH, Jeannie M. Muir, MD, John G. McCarthy, MD, MSc Walter Reed National Military Medical Center, Bethesda, MD
Introduction: In the United States, schistosomiasis is rare. The majority of schistosomiasis cases occur in Africa due to exposure to contaminated freshwater. In some African populations lacking control programs and water sanitation methods, prevalence of schistosomiasis may exceed 50%. Schistosoma japonicum has been implicated in the carcinogenesis of colorectal cancer with infected individuals having a three-fold increase of developing colorectal cancer. We present a case of a sigmoid polyp with high grade dysplasia found in a patient with rectal schistosomiasis.
Case Description/Methods: A 46-year-old Ugandan man presented to the gastroenterology clinic for evaluation of new scant hematochezia in the setting of transient constipation. Family history was negative for polyps or colorectal cancer. Rectal exam and hematocrit were normal. On colonoscopy, a 2cm pedunculated tubulovillous adenoma with high grade dysplasia was removed from the sigmoid colon. A separate 2mm sessile polyp was removed from the rectum, with pathology revealing scattered helminth eggs consistent with Schistosoma species in the lamina propria with overlying unremarkable rectal epithelium. Subsequent serum Schistosoma antibody IgG was positive, while stool and urine samples were negative for ova or parasites. Based on the patient’s travel history, the parasite was likely Schistosoma hematobium or S. mansoni. The patient took two doses of oral praziquantel, and there has been no recurrence of symptoms.
Discussion: Chronic intestinal schistosomiasis most often presents with poorly characterized abdominal pain and may be asymptomatic. Endoscopically, these cases can have subtle findings such as mucosal edema and small ulcerations or present as colorectal cancer. Schistosomiasis associated colorectal cancer (SACC) is thought to have biological behavior similar to colitis-induced colorectal cancer with a strong predilection for the sigmoid colon and rectum. While most commonly associated with japonicum due to high egg output, it is possible that other Schistosoma species also place infected individuals at higher risk of colorectal cancer. This case represents a rare presentation of schistosomiasis in a patient with a high-risk adenoma; an association gastroenterologists should consider in patients from endemic areas.
Figure: Helminth eggs, consistent with Schistosoma spp., with associated granulomatous and eosinophilic inflammation within the rectal lamina propria at low (A, B hematoxylin and eosin at 100x) and high (C, D H&E at 400x) magnification.
Kathryn Driggers indicated no relevant financial relationships.
Amy Austin indicated no relevant financial relationships.
Jared Magee indicated no relevant financial relationships.
Jeannie Muir indicated no relevant financial relationships.
John McCarthy indicated no relevant financial relationships.
Kathryn E. Driggers, MD, Amy L. Austin, MD, Jared S. Magee, DO, MPH, Jeannie M. Muir, MD, John G. McCarthy, MD, MSc. P1204 - Schistosomiasis in an American Service Member: The Value of Travel History in Colorectal Cancer Screening, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.